I had a day off today, and a few things I wanted to try out. So I put together this test mule. Test results so far:

1) CLB side-pull calipers are really nice
2) a Gazelle A frame does have enough clearance for fenders
3) old Campagnolo 9-speed ergos do indeed work well with a modern Shimano rear derailleur and a 5-speed FW
4) and the ratcheting mechansim in the left lever works nicely and has a big enough range to cover a triple

All in all a setup that would make a nice lightweight credit card touring machine. For such an application I would change to MAFAC center-pulls, though. Both for looks and the ability to mount one of those nifty mini front racks. And a slightly taller frame.